Lovely, thanks a lot for posting this. It does seem this causes an error however during getting the index of Sorted Target Locs in the bottom left, piped into the while condition. To fix this just add a Clamp (Int) with min set to 0 after the Target Index Stepper - 1 call. As far as I can see it still works that way.
Works great for me either way, just thought I’d mention it.